1. Subject
The subject invention relates to an apparatus and method for receiving data via a telephone modem, converting the data from a first binary code to a second binary code and formatting the data for printing on a remote user's printer. More particularly the invention relates to an apparatus which can be remotely programmed over a synchronous line to perform customized data conversion for use by a printer of arbitrary configuration.
2. Description of the Prior Art
Presently data bases are accessed via such devices as telephone modems where the data is transferred from a data source, or host, to an end user desiring the data. This data is transferred over telephone lines in the form of voice/data signals, generally in one or the other of two common protocols, either EBCDIC or ASCII. Most newer printers recognize only the ASCII protocol, so if the data is transmitted in EBCDIC, a code conversion is required. Moreover, special formatting is generally required for supporting the specific needs of the printer. The required customizing is generally accomplished by a dedicated hardware interface. This severely limits the type of printer which may be employed and makes it difficult to change printing units.
It is well known to access a data base using a personal computer or the like and to cause the data base to respond by transmitting text codes and printer control codes in a generic format. Such prior art systems typically store the received information on disk or in RAM for later accessing by local software which is specially configured to drive a specific printer that happens to be connected to the computer. Such systems tie up a computer at the receiving end and are not suitable for high volume use. In high volume situations such as exist in large law offices where many lawyers are in frequent communication with a remote legal data base, it is desirable to provide central printers which are directly driven by data base transmissions.
At the present time an end user cannot simply take a standard printer and connect it to a modem in direct communication with a data base. Printers typically respond to control codes generated by a "function table". These codes provide the driving signals which cause the printer to print recognizable alphanumeric characters. They also provide the formatting which must be handled in a manner dependent upon the specific design of the printer. For example, the text must be printed across the page with a given spacing. Some printers use the so-called proportional spacing between adjacent characters which spaces the characters across the page in varying pitches depending on the number of letters or words which are written across the page on that given line. Other printers use 10 pitch or 12 pitch spacing which indicates that the spacing of the characters is 10 per inch or 12 per inch, respectively. Special codes must be generated to accomplish such spacing. Other codes are necessary to handle printing justification and to position the first line, right margin, left margin and last line of printing, to name just a few. These and other codes must be incorporated into a table, which is organized for access by the printer.
The problem which exists in the market today is that different printers generally use different formats for printing. For word processing operations, function tables are typically specified or installed with a word processing program when the system is first installed. If the software does not support the specific printer, then specialized printer function tables must be written. However, there is presently no mechanism for a remote data base to specify a printer function table or other codes which are needed by the printer to correctly format the output data into a useable output format.
One prior art patent, U.S. Pat. No. 4,754,428 to Schultz, et al shows an apparatus for distributing documents to printers having different formats. This apparatus is disclosed as being useful with electronic mail, where one originating word processing system needs to communicate with several printing stations for hard copy printing. At each location, the printers may be of a different manufacturer, thereby requiring different control codes and formats.
In Schultz et al the word processor broadcasts generalized printer commands without specific formatting codes, proceeding on the basis that most printers operate using the same general printer commands. A communicator is located serially between the text source and the printer at each printing location. The communicator receives the commands intended for the printer and simulates the operation of the printer by sending appropriate response signals to the computer or word processor. The communicator further includes a memory for storing text information which is to be displayed or printed at a later point in time. It also has a printer interface which receives generalized printer command data signals and responds by generating particular command signals in the protocol needed to drive the particular printer being used at the local station. No means are required or provided for remote programming of the communicator.
Another prior art device receives text signals from a data base in EBCDIC protocol and converts them to ASCII protocol for use in driving a dedicated ink jet printer. Protocol conversion and printer control code generation is accomplished by a hardware arrangement which is both specific and permanent.